The prior art has long recognized the demand for decaffeinated beverages such as coffee and tea. Primarily, however, the previously utilized decaffeination techniques have involved the use of organic solvents such as trichloroethylene or chloroform to treat either the vegetable material itself or an aqueous extract thereof, with subsequent separation of caffeine-laden organic solvent, so as to allow further processing of the beverage.
These solvent-based decaffeination techniques have several obvious disadvantages. Organic solvents, and their post-treatment to permit reuse, constitute a considerable operational expense. The solvents are often toxic and therefore require careful separation from the eventual beverage product. The solvents are often highly volatile thus requiring careful plant maintenance as well as ample ventilation in order to ensure the safety of workers. Additionally, various organic solvents indiscriminately solubilize many beverage constituents. Thus, their resultant solutions may require further treatment to isolate and permit re-incorporation of desirable solubles into the beverage product.
In view of these and many other problems which have been encountered in using organic solvents for decaffeination, it is understandable that a multitude of complex techniques have been evolved in order to minimize their drawbacks. In addition, some attempts have been made to avoid their difficulties entirely by dispensing with caffeine solvents while researching totally different process means.
U.S. Pat. No. 2,151,582 of Block exemplifies such attempts to avoid the use of organic solvents. This patent describes various uses of carbon adsorbents to decaffeinate coffee extract. Because of the high strength of the carbon affinities for coffee constituents, however, subsequent regeneration of the carbons is impractical. Accordingly, these techniques proved too expensive for commercialization and were abandoned.
In accordance with the process of U.S. Pat. No. 3,108,876 of Turken et al, ion exchange resins may be employed to decaffeinate a coffee concentrate. As the patent teaches, however, the ion exchange resins also remove important noncaffeine constituents and drastically lower the pH of the concentrate. Accordingly, treatment of the decaffeinated concentrate with artificial neutralizing agents is taught to be necessary to raise its pH to a normal value and refurbish its mineral content. Such agents do not derive from the coffee itself; however, and the resultant adulterated product has not proven successful.
The foregoing patents exemplify the state of the art with respect to non-solvent decaffeination of vegetable materials such as tea and coffee. Thus, although considerable effort has been expended on such alternative processes, commercial scale decaffeination remains dependent on caffeine solvent based extractions.